Plasma Circulating Tumor DNA Analyses in ER+ Metastatic Breast Cancer

Inclusion Criteria:

• Age ≥ 18 years of age
• Female gender
• Biopsy proven diagnosis of breast cancer
• Stage IV disease diagnosed either by radiographic studies or biopsy
• ER+ by immunohistochemistry on primary and/or metastatic tissue biopsy (>10%)
• HER2 non-amplified (1+ or below by immunohistochemistry, and/or Her2 FISH <2 HER2-to-CEP17 ratio)
• Progressed on at least one prior line of endocrine therapy for metastatic disease
• Three or fewer prior endocrine-containing therapies for recurrent/metastatic disease
• Two or fewer prior lines of cytotoxic chemotherapy for recurrent/metastatic disease
• Plans to initiate 2nd, 3rd, or 4th line endocrine therapy for metastatic disease
• Recent re-staging scans within 4 weeks of study enrollment, with radiographically identifiable disease
• No concurrent or prior diagnosis of malignancy other than breast cancer for the past 5 years. Patients with a history of in situ cancer or basal or localized squamous cell skin cancer remain eligible
• Intends to pursue treatment as well as clinical and radiographic follow-up at UNC Health Care
• Signed an institutional review board (IRB)-approved informed consent document for this protocol and HIPAA consent form

Exclusion Criteria:

• < 18 years of age
• Tissue biopsies that support the presence of both ER+ and ER- metastatic breast cancer in the same patient
• Dementia, altered mental status, or any psychiatric condition that would prohibit the understanding or rendering of informed consent
• Pregnant or lactating women